I am simulating a box with the non periodic boundary conditions in z direction and periodic boundary conditions (pbc) along x and y in LAMMPS. I want to know that how the pressure tensor is calculated in this system with no pbc along z? Does this non periodicity of box would affect the calculation of pressure tensor in LAMMPS or it would be calculated in the same way as in the case of pbc?
Dear Jagroop,
it seem like you cannot apply non-PBC within NpT ensemble (in which case the pressure tensor is determined).
In my opinion you can use NVE within non-PBC only! So in this case, the pressure is not to be determined "to be more constant". You can output in this case all the P components, and plot to check what's going on with the components (especially Pxz, Pyz and Pzz). Conservation laws of the energy are supposed of course to be satisfied, but pressure tensor in another story.
PS: Of course you could compile some of the LAMMPS /scr-directory scripts to make possible to run a simulation without an error, while keeping NpT+(nonPBC), but the system would be NOT a physical one, not real.
My advise is: Use nonPBC, try NVE and analyze the tensor every timestep until equilibrium.
Hope it helps.
Thank you Kostadin Georgiev for your response. This is an useful information.
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